Modern elevator systems often include distributed intelligence in the form of elevator car controllers, such as microprocessors.
In some modern elevator systems channeling is used as a means of ensuring smooth traffic flow during up-peak. The assignment of cars to a Sector, also referred to as a channel or zone, is done at the time the car reaches a lobby commitment point during the car's descent to the lobby. The assignment is accomplished in accordance with a round-robin arbitration technique, wherein the elevator car controller communicates with other elevator car controllers to determine which Sectors are already assigned, and then assigns to itself a next available Sector.
A Sector is comprised of one or more contiguous floor landings that are to be served by an elevator car after it leaves the lobby. The lobby commitment point is generally near to the lobby floor, and coincides with a Control Stop Point (CSP), where the elevator car begins to decelerate.
A result of this approach is that the assignment of the elevator car to a Sector may occur but a few seconds before the car reaches the lobby. After assignment, the elevator car provides a lobby display indicating which floors it will be servicing when it ascends.
However, due to the potentially large number of people waiting in the lobby during up-peak periods, situations may arise where it is difficult for passengers to physically move to the elevator car that is assigned to a Sector that includes the passenger's desired floor landing. Also, passengers must constantly monitor the lobby displays of all the cars so that they can move to the proper car.
In commonly assigned U.S. Pat. No. 4,363,381, issued Dec. 14, 1982, entitled "Relative System Response Elevator Call Assignments" to J. Bittar there is described an elevator system in which hall calls registered at a plurality of landings are assigned to cars on the basis of a summation of relative system response factors for each car, relative to each registered hall call.
Commonly assigned U.S. Pat. No. 4,305,479 issued Dec. 15, 1981, entitled "Variable Elevator Up Peak Dispatching Interval" to J. Bittar et al. describes a group controller that provides a variable interval between dispatching of elevator cars from a lobby during up-peak, the dispatching interval being controlled by an approximate round trip time of an elevator being dispatched from the lobby in serving the car calls registered within it and returning to the lobby, or the average of the approximate round trip time for two or three most recently dispatched elevator cars. The dispatching interval is determined by the approximate round trip time divided by the number of elevator cars serving the up-peak traffic. In addition, the dispatching interval can be further reduced in dependence upon the number of cars standing at the lobby, the reduction being greater for the case wherein the last car leaving the lobby is not more than half full, than in the case when the last car leaving the lobby is more than half full.
Commonly assigned U.S. Pat. No. 4,838,384, issued Jun. 13, 1989, entitled "Queue Based Elevator Dispatching System Using Peak Period Traffic Prediction" to K. Thangavelu describes a combined prediction technique to assign hall calls to cars on a priority basis for floors having a predicted high level of passenger traffic. During up-peak periods the lobby is given high priority, with a lobby passenger queue being predicted using passenger arrival rates and expected car arrival times.
It is an object of this invention to provide an elevator system that provides for an elevator car Sector assignment to be accomplished at an earlier point than the conventional lobby commitment point.
It is a further aspect of the invention to provide an elevator system wherein sectoring assignments are accomplished at or soon after an elevator car turn around point.